Laryngoscopy with or without endotracheal intubation amounts to a highly noxious stimulus to the haemodynamics of a patient and various efforts have been made to attenuate this response. This study was conducted to compare the effects of oral Clonidine and IV Clonidine premedication on haemodynamic response to laryngoscopy and endotracheal intubation. This is a prospective, randomized controlled, double blind study conducted after obtaining institutional ethical approval. One hundred normotensive patients between 18-45yrs of age (ASA Grade I & II) scheduled for elective surgery were sub-divided into two groups with 50 patients in each group. Oral or intravenous clonidine 3μg/kg was given at 30 and 15 minutes before induction. Patients were Induced with inj Propofol 2.5 mg/kg, fentanyl 1μg kg-1 and inj Vecuronium 0.12mg/kg and intubated. Heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), rate pressure product (RPP) were recorded at Basal (before administration of study drug), pre laryngoscopy (after administration of study drug but before induction of anaesthesia) and post laryngoscopy at 1, 3, 5, 10 and 15 minutes respectively. HR, SBP, DBP, and RPP decreased by -3.6%, -9.5%, - 11.5%, -12.7% in the oral clonidine group and by -3.4%, -16.3%, -11.9%, -19.1% in IV clonidine group from basal to pre laryngoscopy values (p<0.05). An increase was seen in both the group at 1, 3 and 5 minutes after intubation in both the groups. But the response was significantly less in the IV Clonidine group as compared to the Oral group. All the variables returned towards baseline values by 10-15 minutes post-laryngoscopy in either group. Oral Clonidine 3μ/kg was less effective than IV Clonidine 3μg/kg in blunting haemodynamic stress response. IV Clonidine premedication effectively blunted stress response to endotracheal intubation in ASA physical status I and II patients without causing adverse reactions.

Bostana, H., and Eroglu, A. (2012). Comparison of the clinical efficacies of fentanyl, esmolol and lidocaine in preventing the hemody-namic responses to endotracheal intubation and extubation. Journal of Current Surgery, 2: 24-28.